The present invention relates to a process for producing L-phenylalanine. More particularly, the present invention relates to a process (process I) for producing L-phenylalanine which comprises culturing a microorganism belonging to the genus Citrobacter, Erwinia, Enterobacter, Klebsiella, Microbacterium, Salmonella, Bacillus, Corynebacterium or Flavobacterium having the ability to convert phenylpyruvic acid into L-phenylalanine in the presence of an amino group donor, in a culture medium containing phenylpyruvic acid and an amino group donor or alternatively, causing cells of the microorganism or product of treatment thereof to react on phenylpyruvic acid and an amino group donor in an aqueous solution: forming L-phenylalanine in the resultant culture broth or aqueous solution;and recovering L-phenylalanine therefrom.
Furthermore, the present invention relates to a process (process II) for producing L-phenylalanine which comprises culturing a microorganism belonging to the genus Serratia, Escherichia, Pseudomonas, Enterobacter, Salmonella, Erwinia, Proteus, Citrobacter, Paracoccus, Arthrobacter Bacillus, Brevibacterium, Corynebacterium. Flavobacterium, Klebsiella, Kluyvera or Micrococcus having the ability to convert phenylpyruvic acid into L-phenylalanine in the presence of fumaric acid and ammonium ion or urea, in a culture medium containing phenylpyruvic acid, fumaric acid and ammonium ion or urea or alternatively, causing cells of the microorganism or product of treatment thereof to react on phenylpyruvic acid, fumaric acid and ammonium ion or urea in an aqueous solution; forming L-phenylalanine in the resultant culture broth or aqueous solution and recovering L-phenylalanine therefrom.
L-phenylalanine is an amino acid which is useful as a raw material for a sweetening agent. It is an object of the present invention to provide an improved process for production of such amino acid on an industrial scale at low cost.
Heretofore, as the enzymatic processes for producing L-phenylalanine using phenylpyruvic acid as a susbstrate, the processes which cause cells of microorganisms belonging to the species Agrobacterium tumefaciens or Proteus vulgaris (Amino Acids, Vol. 2, page 18, 1960), the genus Alcaligenes, Pseudomonas, Aerobacter, Escherichia, Achromobacter, Sarcina, Kluyvera, or Micrococcus (Japanese Published Examined Patent Application No. 10672/62), the species Serratia marcescens (Amino Acids, Vol. 5, page 61, 1962), or the genus Aspergillus, Absidia, Cheatomium, Fusarium, Penicillium, Mucor, Monascus or Rhizopus (Japanese Published Examined Patent Application No. 20556/70) to react on phenylpyruvic acid and amino acids as amino group donors; and the processes which cause phenylpyruvic acid and amino group donors [such as nylon cylic oligomer (Japanese Published Examiner Patent Application No. 17991/69), nylon 6 hydrolyzate (Japanese Published Examined Patent Application No. 17992/69) and lactam (Japanese Published Examined Patent Application No. 17990/69)]to react on cells of a microorganism of the genus Corynebacterium have been known.
Although the processes exemplified above result in improved yields of L-phenylalanine, the production yields of such processes, nevertheless, are comparatively low from a commercial application standpoint. Thus, a need exists for a process for producing L-phenylalanine in higher yields at low cost.
To this end, it has now been found that L-phenylalanine is produced in higher yields by using the process of this invention; that is, process I or process II.